Morphine-induced Miosis: In the anesthetized dog, it was possible to record the unitary activity of the visceral nucleus (neuron) of the occulomotor nuclear complex. Morphine Actions on the Apneustic Neurons: It was previously reported that morphine depressed neuronal activity of neurons in the apneustic center. We propose to record these neurons with microelectrode and to ascertain if morphine depression is specific on these neurons. Morphine-induced Hyperthermia: The neurons in the PO/AH regions have thermoregulatory function. It was reported that morphine produced hypertherma. It is therefore proposed to determine if morphine depresses the activity of these neurons. Morphine and Other Agents on the Limbic System: It has been suggested that limbic system plays a very important role in behavior. Nevertheless, very little is known about morphine action on the unit activity of the limbic system. It is hoped that by using micro- electrodes, it is possible to correlate the neuronal activity with behavior.